Demographic eradication is not catchy or memorable. Thus it lacks the defining quality of a "meme". You can quibble with the term white genocide but it is at least thought-provoking and it has proven its effectiveness in Darwinian fashion by having survived in a world of competing memes.

In Europe, the meme "Great Replacement" has caught on throughout much of the continent, with essentially the same meaning as "White Genocide". I suggest you use that if you don't like "White Genocide".

On pragmatic grounds, we have to go with what has been shown to be to some degree effective or memorable rather than attempt to invent ideal might-have beens.